Cryptosporidium species are obligate intracellular apicomplexan parasites that infect the intestinal epithelium of a wide range of vertebrates, causing gastroenteritis and diarrhea that can be severe in young animals and dangerous, sometimes life-threatening, in immunocompromised people. Unlike many enteric pathogens, Cryptosporidium oocysts are remarkably resistant to environmental stress and to standard water-treatment disinfection, which makes even asymptomatic carriers relevant to public health. Because infected animals shed infectious oocysts in their feces without necessarily showing signs of disease, understanding which species inhabit which hosts is central to assessing transmission risk on farms and in watersheds.

The research team, led by Sümmani Çifci of Aksaray University together with colleagues at Erciyes University, focused on the Akkaraman breed, a hardy indigenous sheep breed that dominates the flocks of Central Anatolia. Between the provinces of Nevşehir, Sivas, and Kayseri, the investigators collected fresh fecal samples from 300 healthy Akkaraman sheep, one hundred animals per province, drawn randomly from a variety of small-scale farms. Restricting the survey to clinically healthy animals was a deliberate choice: it allowed the team to measure the burden of subclinical infections, the silent reservoir that conventional disease surveillance tends to miss.

In the laboratory, genomic DNA was extracted from each sample and screened for Cryptosporidium using polymerase chain reaction (PCR), a technique that amplifies parasite-specific DNA sequences to levels that can be detected even when oocyst numbers are low. Positive samples then underwent sequence analysis of the 18S ribosomal RNA gene, the standard genetic barcode for distinguishing Cryptosporidium species, whose oocysts are morphologically nearly identical under the microscope. The resulting sequences were compared against reference databases and used to build phylogenetic trees, placing each isolate within the parasite’s evolutionary framework.

The headline result was an overall prevalence of 6.0 percent, with 18 of the 300 sheep testing positive for Cryptosporidium. Sequence analysis resolved these infections into three species: Cryptosporidium parvum and Cryptosporidium bovis each accounted for seven animals, corresponding to 2.3 percent of the flock sample, while Cryptosporidium xiaoi was found in four animals, or 1.3 percent. The team deposited the sequences in the GenBank database under accession numbers MZ027074 through MZ027078, making them available for future comparative studies worldwide.

The detection of C. bovis in sheep is the study’s most striking claim. As its name suggests, C. bovis is primarily a cattle parasite, typically associated with subclinical infections in post-weaned calves and adult bovines. Finding it in ovine hosts in Türkiye is, according to the authors, a first for the country and adds to a growing international literature showing that host boundaries among Cryptosporidium species are more permeable than once assumed. Such cross-species spillover matters because it hints at possible transmission between cattle and sheep sharing pasture, water sources, or farm infrastructure, and because it complicates the simple assumption that each livestock species carries its own characteristic parasite fauna.

The other two species found carry their own significance. C. parvum is the most clinically important Cryptosporidium in mammals and a major zoonotic agent, responsible for a large share of human cryptosporidiosis cases worldwide, including outbreaks linked to contaminated drinking water. Its presence in apparently healthy ewes and rams underscores that even symptom-free sheep can contribute oocysts to the environment. C. xiaoi, by contrast, is considered largely host-adapted to sheep and goats and is generally of lower zoonotic concern, though it has been documented in periparturient transmission from ewes to lambs. The mixture of zoonotic and host-adapted species within a single flock profile illustrates the epidemiological complexity of ovine cryptosporidiosis.

Statistical analysis of the survey data added an age dimension to the picture. Positivity rates differed significantly across age groups, with a p-value below 0.0001, indicating that the probability of detecting Cryptosporidium DNA was far from uniform among young and older animals. This pattern is consistent with the biology of the parasite: young lambs are typically more susceptible to active infection and higher oocyst shedding, while adults more often harbor transient or low-level infections. Notably, no significant difference emerged between male and female sheep, with a p-value of 0.548, suggesting that sex does not meaningfully shape infection risk in this population.

Phylogenetic analysis reinforced the coherence of the species identifications. The Anatolian isolates clustered within the same clades as reference sequences reported from different hosts and geographic regions, meaning that the Turkish parasites are genetically consistent with their counterparts elsewhere rather than representing divergent local lineages. This kind of global genetic continuity is exactly what allows molecular epidemiologists to trace potential transmission routes across farms, regions, and even countries, and it strengthens confidence that the species assignments were not artifacts of sequencing noise.

For the authors, the findings carry a clear practical message: Cryptosporidium infections in sheep deserve active control attention, not only because of their potential impact on lamb health and productivity but because of their public health relevance. Healthy sheep on small-scale farms, the study shows, can silently host both zoonotic C. parvum and the previously unrecorded bovine species C. bovis, contributing to environmental contamination that may reach humans through water, food, or direct contact. As molecular surveillance expands, the team suggests that the true diversity of Cryptosporidium circulating among Türkiye’s small ruminants is likely greater than microscopy-based surveys have revealed, and that continued genotyping will be essential for mapping and ultimately interrupting transmission at the human-animal interface.

Subject of Research: Molecular prevalence and species characterization of Cryptosporidium parasites in sheep in Central Anatolia, Türkiye

Article Title: Molecular Characterization of Cryptosporidium spp. in Sheep from Central Anatolia: First Report of Cryptosporidium bovis in Ovine Hosts in Türkiye

Article References: Çifci, S., Arslanhan, B. A., Önder, Z., & Düzlü, Ö. (2026). Molecular Characterization of Cryptosporidium spp. in Sheep from Central Anatolia: First Report of Cryptosporidium bovis in Ovine Hosts in Türkiye. Acta Parasitologica, 71(5), Article 231. https://doi.org/10.1007/s11686-026-01418-7

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01418-7

Keywords: Cryptosporidium, sheep, Akkaraman, Central Anatolia, Türkiye, Cryptosporidium bovis, Cryptosporidium parvum, Cryptosporidium xiaoi, 18S rRNA, molecular epidemiology, zoonosis, prevalence